Goals for the immediate future for the project entitled "Tritiated Peptides/Proteins in Endocrine Biochemistry" are: a) to extend studies of the labeling mechanism, based upon the tritium atom hypothesis proposed in our initial publication; b) to develop improved techniques for obtaining specific activities approximating 1-2 atoms/molecule by increasing effective tritium atom delivery and/or exchange reactions in peptides and proteins; c) to characterize those structural aspects of oligopeptides which influence the extent and the specific sites of tritium-hydrogen exchange; d) to study several aspects of the metabolism of excretion of H3-ACTH which has been prepared with a specific activity of 29 Curies/mMole and full biological activity as a prototype peptide hormone with no secondary structure; and e) to determine, because of their analogous structural features, the differential effects of the tritium atom reaction upon LH and FSH, utilizing receptor binding, subunit recombination and H3-distribution within the molecule.